Imaging lens and imaging apparatus

Abstract

There is provided An imaging lens including a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power that are configured to be arranged sequentially from an object side to an image side. Focus is achieved by fixing the first lens group in an optical axis direction and moving the second lens group from the image side to the object side when a subject distance is changed from infinity to proximity. The first lens group includes an object-side lens group having a negative refractive power and an image-side lens group having a positive refractive power that are configured to be arranged sequentially from the object side to the image side. In an air space of the first lens group, an air space between the object-side lens group and the image-side lens group is set to be maximum.

What is claimed is: 
     
       1. An imaging lens comprising:
 a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power that are configured to be arranged sequentially from an object side to an image side, 
 wherein focus is achieved by fixing the first lens group in an optical axis direction and moving the second lens group from the image side to the object side when a subject distance is changed from infinity to proximity, 
 wherein the first lens group includes an object-side lens group having a negative refractive power and an image-side lens group having a positive refractive power that are configured to be arranged sequentially from the object side to the image side, 
 wherein, in an air space of the first lens group, an air space between the object-side lens group and the image-side lens group is set to be maximum, and 
 wherein a following Condition Expression (1) is satisfied:
   −13.0 <f 1 F/f 2<−4.0,  (1)
 
 
 where f 1 F is a focal distance of the object-side lens group at an infinity focus time and f 2  is a focal distance of the second lens group at the infinity focus time. 
 
     
     
       2. The imaging lens according to  claim 1 , wherein a following Condition Expression (2) is satisfied,
   1.8 <f 1 /f< 4.5,  (2)
 
 where f 1  is a focal distance of the first lens group at the infinity focus time and f is a focal distance of an entire lens system at the infinity focus time. 
 
     
     
       3. The imaging lens according to  claim 1 , wherein the object-side lens group includes a first lens having a positive refractive power and a second lens having a negative refractive power that are configured to be arranged sequentially from the object side to the image side. 
     
     
       4. The imaging lens according to  claim 1 , wherein the second lens group includes two pairs of cemented lenses. 
     
     
       5. The imaging lens according to  claim 1 , wherein each of the first lens group and the second lens group includes at least one aspheric lens. 
     
     
       6. The imaging lens according to  claim 1 , wherein, when the subject distance is changed from infinity to proximity, the aperture stop and the second lens group are integrally configured and moved from the image side to the object side. 
     
     
       7. An imaging apparatus comprising:
 an imaging lens; and 
 an image sensor that converts an optical image formed by the imaging lens into an electric signal, 
 wherein the imaging lens includes a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power that are configured to be arranged sequentially from an object side to an image side, 
 wherein focus is achieved by fixing the first lens group in an optical axis direction and moving the second lens group from the image side to the object side when a subject distance is changed from infinity to proximity, 
 wherein the first lens group includes an object-side lens group having a negative refractive power and an image-side lens group having a positive refractive power that are configured to be arranged sequentially from the object side to the image side, 
 wherein, in an air space of the first lens group, an air space between the object-side lens group and the image-side lens group is set to be maximum, and 
 wherein a following Condition Expression (1) is satisfied:
   −13.0 <f 1 F/f 2<−4.0,  (1)
 
 
 where f 1 F is a focal distance of the object-side lens group at an infinity focus time and f 2  is a focal distance of the second lens group at the infinity focus time.